1. Field of the Invention
The present invention relates to a disc cartridge configured to be capable of accessing a disc-shaped recording medium accommodated within a cartridge body via an disc access opening.
2. Description of the Related Art
A disc cartridge of the above-mentioned kind is disclosed in Japanese Laid-Open Patent Publication (Kokai) No. 2003-123426, which contains an information recording medium within a cartridge housing thereof. This disc cartridge includes a disc-shaped information recording medium, a cartridge housing having an upper shell and a lower shell, an inner shell serving as a disc tray, and a pair of shutter members (shutters) arranged between the inner shell and the lower shell. The lower shell has a disc access opening formed therein for allowing access to the information recording medium contained in the disc cartridge, and is attached to the upper shell. The inner shell has a disc access opening formed therein such that it has the same shape and size as those of the disc access opening of the lower shell, and is pivotally accommodated within the cartridge housing in a manner sandwiched between the upper shell and the lower shell. When the disc cartridge is loaded in and discharged from a recording and reproduction device, the inner shell is pivotally moved relative to the cartridge housing by the recording and reproduction device, to thereby open and close part of the disc access opening of the lower shell. The shutter members are pivotally supported on the inner shell, and pivotally moved relative to the inner shell by pivotal motion of the inner shell. Further, the pair of shutter members are pivotally moved in accordance with the pivotal motion of the inner shell, and brought into abutment with each other to open and close another part of the disc access opening of the lower shell, thereby opening and closing the disc access opening in cooperation with the inner shell. Thus, in this disc cartridge, when it is loaded in the recording and reproduction device, the disc access opening is opened to allow access to the information recording medium, and when it is discharged from the recording and reproduction device, the opening is closed by the inner shell and the shutter members to restrict access to the information recording medium.
From the study of the disc cartridge described above, the present inventors found out the following points for improvement: The disc cartridge is configured such that when it is discharged, the inner shell is pivotally moved relative to the cartridge housing by the recording and reproduction device, thereby causing the pair of shutter members to be pivotally moved relative to the inner shell, whereby the opening is closed by the inner shell and the shutter members. In this case, to pivotally move the inner shell relative to the cartridge housing smoothly, it is necessary to provide in advance a certain degree of gap between the cartridge housing and the inner shell. Similarly, to pivotally move the shutter members relative to the inner shell smoothly, it is necessary to provide in advance a certain amount of gap at the pivotally supported portions (between a shaft and shaft holes) of the shutter members supported on the inner shell. This produces slight play between the cartridge housing and the inner shell, and between the inner shell and the shutter members. As a result, in the conventional disc cartridge, the shutter members, which are in a closed state in which they are brought into abutment with each other to close the opening, are sometimes slightly moved (pivotally moved) with respect to the inner shell. This sometimes produces a small gap between the shutter members. Therefore, the conventional disc cartridge suffers from the problem that dust can enter the cartridge housing due to the gap formed between the shutter members.